Photographic imaging of material containing halo azido naphthalenes

ABSTRACT

NOVEL HALO AZIDO NAPHTHALENES AND DRY PHOTOIMAGING PROCESSES AND COMPOSITIONS EMPLOYING SAID NAPHTHALENES ARE DISCLOSED.

3 o. 3 .l 8 5 7 l 3 G N T1. N I A T w 1 C 7 S9 LEl AN IE f RLG mm2 HATYGMHa MM rf m3@ sGOl .w mm BMM l mom C IHi m A R G O T O H P sept. 11,1973 United States Patent 3,758,303 PHOTOGRAPHIC IMAGING OF MATERIALCON- TAINING HALO AZIDO NAPHTHALENES Balwant Singh, Stamford, Conn.,assignor to American Cyanamid Company, Stamford, Conn. Originalapplication May 26, 1971, Ser. No. 147,117, now Patent No. 3,699,130.Divided and this application Aug. 2, 1972, Ser. No. 277,453

Int. Cl. G03c 5/18 U.S. Cl. .96-27 R 6 Claims ABSTRACT OF THE DISCLOSURENovel halo azido naphthalenes and dry photoimaging processes andcompositions employing said naphthalenes are disclosed.

This application is a divisional of application Ser. No. 147,117, tiledMay 26, 1971, now Pat. No. 3,699,130. This invention relates to certainnovel halo azido naphthalenes and to dry photoimaging processes andcompositions employing said compounds.

Photosensitive compounds, compositions and processes play an essentialrole in photography and the related arts dealing with the formation ofimages with the aid of some activating influence, Vsuch as light, heat,etc. For many applications, as in the case of printing on white paper,it is desirable to maximize the neutrality of the image, in addition toachieving good color stability, speed, acuity, resolution and tonalrange as well as to achieve the convenience of a dry imaging processemploying relatively inexpensive materials.

Accordingly, it is an object of the present invention to providephotosensitive compositions which are suitable for the formation ofimages having broad spectral characteristics as well as good imagestability, acuity, resolution vand tonal range. It is a further objectto provide a convenient, dry photoimaging process for the formation ofsuch images. These and other objects of the present invention willbecome apparent from the description and examples which follow.

In copending application Ser. No. 82,129, tiled Oct. 19, 1970, the useof 1,8-diazidonaphthalene and 8azido1 naphthylamne in photoimaging wasdisclosed. It has been unexpectedly found that images of enhancedneutrality and optical density can be achieved by employing the novelhalo azido naphthalenes selected from the group consisting of:

wherein Y is a member selected from the group consisting of N3 and -NH2.

While applicant does not wish to be limited to a specific theory, it isbelieved that the halo substituents function as internal heavy atoms toproduce internal spin orbital coupling inthe image forming process.

The photosensitive compounds can be readily prepared by chlorination orbromination of the known compound, y8-azido-lnaphthylamine. This can beaccomplished by conventional halogen'ation procedures such as those setforth in the text entitled, Reactions of Organic Compounds by W. J.Hickenbottom, Longmans, Green and C0., London, NewYork, 1936, pp.291-293.

ice

Introduction of the halo substituents may be graphically illustrated asfollows:

wherein X is Cl or Br.

The corresponding dihalo 1,8-diazidonaphthalenes can be readily formedby converting the amine function to an azide function by conventionalprocedures such as those disclosed, for example, in U.S. Pat. No.3,123,621.

The novel, photosensitive compounds of the present invention are8azido-2,4dibromol-naphthylamine, 8-azid0- 2,4-dichloro 1 naphthylamne,1,8-diazido-2,4dibr0m0 naphthylamne and 1,8-diazido 2,4dichloronaphthylamine.

The photosensitive materials of the present invention comprise asuitable photographic substrate having a photosensitive film or coatingdeposited thereon. The coating is composed of conventional film-formingplastics having one or more of the above photosensitive compoundsuniformly incorporated (preferably dissolved) therein.

Suitable substrates include, for example, such materials as paper,plastic, wood, metal and glass.

Among the suitable conventional polymeric binders, one may mention, forexample, polyvinyl chloride, polyethylene, polymethylmethacrylate,polyvinyl acetate, cellulose acetate, copolymers of the correspondingmonomers, copolymers of vinylidene chloride and acrylonitrile andmixtures of the above polymers.

Incorporation of the photosensitive compounds Within the film-formingpolymer can be conveniently achieved by selecting an organic solvent inwhich both the polymer and photosensitive compound are soluble. Suitablesolvents include for example toluene, tetrahydrofuran, benzene, methylethyl ketone, mixtures of the above and the like. The resulting solutioncan be applied to the substrate of choice by a variety of standardcoating techniques Of the suitable methods of applying the sensitizeddope to the structure, the Fixed Blade Method, the Imbibing Method andthe Meyer Rod Method are among the preferred techniques.

In the Fixed Blade Method, the base material is positioned under a fixedblade and an excess of the coating material is placed on the base. Thebase is then passed under the blade to produce a uniform coating havinga thickness detetrmined by the distance between the mounted blade andthe base material.

In the Imbibing Method, a base stock having a plastic surface is coatedwith the active compound by passing it under a roller, touching asolution of the azido cornpound. The excess coating is removed from thesurface by an air knife. By way of illustration, one may mention passingpaper coated with polyvinyl chloride, polyvinyl acetate orpolymethylmethacrylate through a solution ofl,8-diazido2,4dibromonaphthalene in a solvent such as tetrahydrofuran,methyl ethyl ketone, acetone or toluene or mixtures thereof.

The concentrations of the photosensitive compound and thickness of thecoating applied to the substrate may be varied to tailor thephotosensitive system so as to achieve the desired degree of imageintensity, speed, etc. Optimum concentrations and thicknesses will, ofcourse, vary depending upon the particular photosensitive compound,binder material, coating thickness, temperature, time, and otherfactors. In general, satisfactory photoimages can be produced byemploying binder compositions having from about to about 20% by weightof the photosensitive compound and coatings having thicknesses in therange of from about 0.05 to about 1.50 mils. Preferred concentrationsand thicknesses are about by weight and about 0.3 mil, respectively.

The aromatic azido compounds are themselves generally sensitive toradiation containing wavelengths within the ultraviolet region. By meansof the addition of a sensitizing agent to the polymer binder, thesensitivity can be extended into the range of from 360 my. to 470 m/r orgreater. The energy transfer of such systems is surprisingly efficientin view of the typically high viscosity of the bindner polymer systemsbeing sensitized.

Several advantages are provided by the use of sensitized systems. Theypermit the use of apparatus equipped with inexpensive and convenientlight sources, such as incandescent lamps, and allow projection printingthrough various optical systems with normal optical glass. They alsopermit the simultaneous use of both direct and indirect excitation ofazido compounds through simultaneous exposure of the photosensitivecompounds to both visible and ultraviolet light. Alternatively, enhancedabsorption can be achieved by using an ultraviolet absorbing sensitizerin combination with the azido composition.

Suitable Sensitizers include, for example, fluoranthene, thioxanthone,fluorenone, perylene, benzanthrone, benzophenone, phenazine andthioacridone.

Sensitizers which absorb light in the visible spectrum are of necessitycolored compounds. Where the colors caused thereby are found to beobjectionable, one may employ a colorless, ultraviolet absorbingsensitizer or a volatile sensitizer, such as, uorenone, in a gaspermeable binder, such as, polyvinyl chloride. The period and degree ofheat treatment is adjusted to be suicient to effect volatilization ofthe uorenone without producing excessive background color-up.

Optimum relative concentrations of the sensitizer and azido compoundwill, of course, vary with the particular system being employed.Generally, energy transfer is favored by high concentrations of thephotosensitive compound. It is preferred to employ the sensitizer in asufficient concentration to absorb the incident light. However,excessively high concentrations of the sensitizer will cause completeabsorption of the incident light at the surface of the plastic matrixand may thereby reduce the eiciency of the system.

Imaging is achieved by exposing the photosensitive compositions topatterned activating radiation, namely, an information containing beamof visible or ultraviolet light.

A convenient source of ultraviolet radiation is provided by lamps whichemit a wide range of ultraviolet frequencies. A light table equippedwith a lm transparency (positive or negative) and a bank ofultraviolet-rich iluorescent lamps, such as, 15 Watt Black Light, No.F15T8-BL by General Electric and Rayonet Photochemical Reactor Lamps,No. RPR 3000A by The Southern New England Ultraviolet Company provides aconvenient source of activating radiation. Conventional azo printingmachines, equipped With high pressure mercury vapor lamps may also beemployed. Since they emit both visible and ultraviolet light, they areespecially well adapted for use with those compositions havingSensitizers to visible light.

Absorption of incident light can be maximized by matching thefrequencies of the incident light with the absorption frequencies of thephotosensitive compound or the sensitizer if one is employed.

Patterning of the activating radiation can generally be achieved by anyof the conventional methods. Suitable methods include passing the lightthrough a lm transparency or a template, use of a cathode ray tubecontaining an ultraviolet phosphor, such as, a Litton Industries, Inc.Cathode Ray Tube, Ser. No. 4188, which contains a P16 phosphor; andusing an ultraviolet pen light, such as Ultraviolet Products, Inc.Pen-Light, or ultraviolet laser, such as might be used in spatialfrequency modulation and halographic information storage, etc.

Optimum periods of irradiation will vary widely, depending upon theparticular photosensitive composition, opacity of transparency, andlight source employed. Exposure for a few Seconds in a conventional azoprinter is generally adequate while periods of two minutes or more maybe required for a source such as the abovementioned light table.

The enhancement of image neutrality and optical density produced by thepresence of the halo substituent is shown in the figure. Thesecharacteristics were observed by irradiating polyester film substrates(Mylar by E. I. du Pont de Nemours) uniformly coated with a layer ofpolyvinyl chloride (Geon 101, d=1.4, by The B. F. Goodrich ChemicalCompany) having a thickness of from about 0.2 to about 0.3 mil which was1.0 N in one of the following photosensitive compounds: 8azido2,4-dibromo-l-naphthylamine, 1,8 diazido-2,4dibromonaph thylamine,-8-azido-1-naphthylamine and 1,8-diazidonaphthylamine. Imaging wasachieved by exposure through a film transparency to a bank of blacklight uorescent lamps transmitting light in the 30D-380 n.m. (peaking at350 n.m.) region for a period of from about 10 to about 30 seconds. Theresult was a gray-black image of excellent tonal range, resolution andacuity in each case. However, the image neutrality and optical densitywere in each case substantially enhanced by the presence of the halosubstituent.

The processes and compositions of the present invention are furtherillustrated by the following examples which are not to be taken aslimitative thereof. All parts and percentages herein are by weightunless otherwise indicated.

EXAMPLE 1 1-amino-8-azido-2,4-dibromonaphthylamine A solution of1-amino-8-azidonaphthylamine (2.3 g., 0.0125 mole) in ml. of glacialacetic acid was treated with a solution of bromine (4.0 g., 0.025 mole)in 50 ml. of glacial acetic acid The precipitated hydrobromide wasremoved by iltration and washed with ether. The nearly white precipitatewas digested with aqueous NaHCO3. The dibromoaminoazide was extractedwith ether, washed, dried and filtered through charcoal. Removal ofether left a residue Which was recrystallized from ether to yield 3.1g., 82% of the desired product having an M.P. of 127 130 C.Identification was made by infrared and elemental analysis:

Calcd. for C10H6N4Br2 (percent): C, 35.10; H, 1.75; N, 16.40; Br, 46.95.Found (percent): C, 35.38; H, 1.46; N, 16.33; Br, 47.19.

EXAMPLE 2 1,8-diazido-2,4dibromonaphthylamine A solution ofl-amino-8-azido-2,4-dibromonaphthylamine (500 mg., 1.46 moles) in 50 ml.of acetic acid was mixed with 10 ml. of concentrated hydrochloric acidand cooled to 5 C. in an ice bath. A solution of NaNOZ (280 mg., 0.4mole) in water (1 ml.) was added dropwise with stirring. After 1/2 hour,the mixture was poured into an excess of NaN3 (2 g., in 100 ml. ofice-water mixture). The precipitate of the diazide was removed byfiltration, dissolved in ethyl ether, dried over anhydrous MgSO4 andfiltered through charcoal. Removal of the ether left the desired productas a residue. It was recrystallized from n-hexane to yield 334 mg.(65%), M.P. 130 C.132 C. Identification was made by infrared andelemental analysis:

Calcd. for CH6N4Br., (percent): C, 32.60; H, 0.90; N, 22.80; Br, 43.50.Found (percent): C, 32.85; H, 0.84;

N, 23.00, Br, 43.75.

EXAMPLE 3 The enhancement of optical density produced by the halosubstituents is demonstrated by the following tests.

Photosensitive compositions were prepared by uniformly coating polyesterlm substrates (Mylar) with layers of polyvinyl chloride (Geon 101) whichwere 0.7 N in the Photosensitive compound. The lms were imaged byexposing them through a film transparency to a Abank of black lightfluorescent lamps transmitting light in the 300-380 n.m. (peaking at 350n.m.) region for various equal intervals of time. The lms werethereafter heated in an oven at 135 C. for sixty seconds and the opticaldensity of each film was thereafter measured. In each case, as shown bythe data presented in Table I below, the bromo substituents produceabout 50% increases in efficiency.

TABLE I 1,8-dlazido- 1,8-diazidonaphtha- 2,4-dibromo- Exposure lenenaphthatime (min.) (OD) lene Thickness of coating=0.2 mil.

plastic having incorporated therein a Photosensitive compound selectedfrom the group consisting of:

Y NaY References Cited UNITED STATES PATENTS 1,845,989 2/ 1932 Schmidtet al. 96-91 N 2,692,826 10/ 1954 Neugebauer et al. 96--91 N X 3,072,4851/1963 Reynolds, et al. 96-91 N X 3,092,494 6/ 1963 Sus et al. 96-75 X3,282,693 11/1966 Sagura et al. 96-49 3,519,424 7/1970 Reynolds et al.96-91 N 3,660,093 5/ 1972 Ranz 96-49 X OTHER REFERENCES Kosar, I.,Light-Sensitive Systems, Wiley & Sons, 1965, pp. 276-282, 330-336,361-363, S-372, 376.

Hoffmann et al., I. Chem. Soc. C0., 1969, pp. 769-772. Reiser et al.,Trans Faraday, Soc., 1968, pp. 1806-1815.

CHARLES L. BOWERS, JR., Primary Examiner U.S. Cl. X.R. 96-49

